Content Gap Analysis is a process of content marketing with the intent of finding those queries that fill the “gap” between current state and future state. Taking your content 1 step further and making it more successful and/or identifying “relevance to alternative searcher intent”.

Essentially you are looking at your primary keywords and discovering gaps you may have missed. Your content covered “this topic” but “may need additional relative keywords based on your study of user intent and keyword relationships.I suggest using Excel for your exercise